1. Field of the Invention
The present invention is directed to an interchangeable postage calculating module and to a corresponding method for data transmission between postage calculating module and a basic device.
2. Description of the Prior Art
A postage calculating module can be used in postage scales and postage meter machine or similar basic devices wherein a debiting takes place.
A number of methods are already known for making postage calculating tables in postage calculating scales interchangeable or reloadable. U.S. Pat. No. 4,506,330 discloses a postage table with switches for address switching stored in a PROM on a removable printed circuit board.
U.S. Pat. No. 3,635,297 discloses a similar interchangeable postage memory table stored in ROMs. The ROM are connected to a parallel bus in order to enable a fast access of a processor thereto.
European Application 0 099 666 likewise discloses a system that operates with a fixed processor and interchangeable fee schedule table memories.
Such solutions with conventional postage structure are flexible only with respect to the table size. In the case of expansions or modifications of fee schedules, the read-only memory with the postage fee schedule table is simply replaced by one having more memory capacity. It is disadvantageous, however, that such replaceable read-only memories are interpreted according to a permanently stored program by the processor in the basic device. Such solutions are therefore restricted to conventional postage structure elements of the program and are inflexible with respect to new postage structure elements. A further disadvantage when accessing the read-only memories with an extensive postage fee schedule table is that adequate speed when accessing requires the use of an expensive interface that must has a number of PINs.
Beginning with a moderate through higher number of letters or other postal matter to be sent, postage meter machines are used in a standard way for franking the postal matter. A postage meter machine is equipped with a control unit, memory means, an input means, a modem or other data reception means, an input/output control means, a display means and a printer, with a prepaid credit balance non-volatilely stored in the memory means. Generally, the control unit CPU is also responsible for the administration of the monetary data, and the postage meter machine is provided with suitable security means. After the subtraction of the determined postage value from the aforementioned credit balance, a stationary print head prints the franking impression column-by-column given simultaneous transport of the letter. A printing width of approximately 1 inch is thereby achieved.
U.S. Pat. No. 4,802,218 primarily discloses methods for chip-card-based accounting of a franking system but also discloses the use of a further chip card on which the current postage fee schedule table is stored. The program of the franking system uses this postage fee schedule table for determining the postage value. Again, however, the serial interface to the chip card with the postage fee schedule table proves to be a bottleneck for processing optimization.
Methods that are not limited to accessing the external read-only memory immediately during the postage calculation, but also can copy or load the current postage fee schedule table into an internal memory area in advance are suitable for avoiding this disadvantage. European Application 0 560 717 discloses a loading plug for such a method for a postage meter machine that includes an internal postage calculator. The fee schedule memory built into the internal postage calculator can be updated subsequently by the user by plugging a loading plug with the new postage table at the exterior of the postage meter machine. The content of the plug is copied into the internal memory of the computer after the actuation of command input means. The user, however, must attend to the loading, including insuring that the internally stored table data are current at all times. Flexibility with respect to future modifications is only available with respect to the table size to the extent that internal memory space therefor was previously planned in.
The postage fee tables are updated from time to time by the mail carrier. Generally, the fees for specific carrier services are thereby raised. Taking all future modifications that are possible into account using a loading plug or by replacement of read-only memories, however, will become more difficult in the future because there is no flexibility with respect to new postage calculating structures, which it must be assumed will be developed
As long as postage meter machines are provided for accounting with one carrier (heretofore, the national (governmental service), the expiration of the old postage fee schedule tables and the necessity of reloading a new table is a procedure that is still monitorable by the manufacturer and the customer, particularly when the postage structures are preserved even though the valves change. A data center remote from the user and the use's postage meter machine can also initiate the communication of a current table, as disclosed in German OS 28 03 982. The postage calculating devices of all customers, however, then must be equipped with a modem or comparable transmission means and must always be kept ready to receive a communication of the updating data. Structure changes cannot be taken into consideration in the calculation. Such a method can also not individually load a specific(different) set of suitable carriers into the postage calculating device for each customer.
U.S. Pat. No. 5,490,077 discloses another method that automatically checks the current status of the internally stored table data after every turn-on of the postage meter machine. Each transmission means thereby requires specific reception or input means. Mobile radiotelephone reception/transmission means are required in a mobile radiotelephone version, a modem is required in an ISDN version and a chip card reader unit is required in a chip card version.
Rapidity in the data access is not necessarily required during loading given all of these loading or copying methods, but such solutions are still inflexible with respect to a fee schedule modification that results in a significantly enlarged fee schedule table, and do not allow any adaptation to a new postage calculation structure.
There is still a need for a postage meter machine which flexibility with respect to the accounting vis-a-vis various carriers. An economically beneficial service would then be selectable from among respective valid (current) fee schedule structures of different carriers. When, however, the postage meter machine is configured for accounting vis-a-vis a number of different carriers, a specific solution must also be created so that the postage fee table valid for the selected carrier is always available. A prerequisite therefor is that adequate memory space be made available in for the different carrier-related fee schedules. It is conceivable, however, that new private carriers in the marketplace which function regionally, nationally or internationally will have postage structures that deviate entirely from previous structures and thus cannot be accommodate in the tables so that the unmodified, old interpretation program could calculate the postage value therefrom. The national postal service as well as private carriers could fundamentally define new postage calculating structures of the fees. In the updating, thus, the interpretation program would also have to be replaced, which raises security considerations specifically in postage meter machines because a program code executed by the postage meter machine computer must always be fashioned according to specific security criteria to guard against manipulation of the monetary data stored in the postage meter machine. The program routines or modifications that are fed in cannot diminish the security against data manipulation. From the viewpoint of the carriers, every possibility for the user to externally reload a program code into the postage meter machine represents an unacceptable security risk because it cannot be precluded that software for the purpose of manipulating the monetary data will be introduced in this way with fraudulent intent. Even if, deviating from the above-recited method, a service technician were to install the new program parts (installation program), fundamental difficulties derive for such an installation procedures, in addition to the costs. The memory space required in the internal memory area for accommodating future postage calculating structures is difficult to plan in advance, and thus the aforementioned installation procedure can still fail under certain circumstances.